The type of the message is pmessage: it is a message received as a result from a PUBLISH command issued by another client, matching a pattern-matching subscription.Messages received as a result of pattern matching are sent in a different format: No other subscriptions will be affected by this call. Will then unsubscribe the client from that pattern. Will receive all the messages sent to the channel, , etc.Īll the glob-style patterns are valid, so multiple wildcards are supported. The Redis Pub/Sub implementation supports pattern matching.Ĭlients may subscribe to glob-style patterns to receive all the messages sent to channel names matching a given pattern. Now the client unsubscribes itself from all the channels using the UNSUBSCRIBE command without additional arguments: UNSUBSCRIBE This is what the first client receives: *3 Wire protocol example SUBSCRIBE first secondĪt this point, from another client we issue a PUBLISH operation against the channel named second: > PUBLISH second Hello ![]() If you need scoping of some kind, prefix the channels with the name of the environment (test, staging, production.). Publishing on db 10, will be heard by a subscriber on db 1. It was made to not interfere with it on any level, including database numbers. Pub/Sub has no relation to the key space. The second element is the name of the originating channel, and the third argument is the actual message payload. Message: it is a message received as a result of a PUBLISH command issued by another client. When the last argument is zero, we are no longer subscribed to any channel, and the client can issue any kind of Redis command as we are outside the Pub/Sub state. Unsubscribe: means that we successfully unsubscribed from the channel given as second element in the reply. The third argument represents the number of channels we are currently subscribed to. Subscribe: means that we successfully subscribed to the channel given as the second element in the reply. The first element is the kind of message: ![]() Format of pushed messagesĪ message is an array-reply with three elements. Messages in streams are persisted, and support both at-most-once as well as at-least-once delivery semantics. ![]() If your application requires stronger delivery guarantees, you may want to learn about Redis Streams. If the subscriber is unable to handle the message (for example, due to an error or a network disconnect) the message is forever lost. Once the message is sent by the Redis server, there's no chance of it being sent again. Redis' Pub/Sub exhibits at-most-once message delivery semantics.Īs the name suggests, it means that a message will be delivered once if at all. Please note that when using redis-cli, in subscribed mode commands such as UNSUBSCRIBE and PUNSUBSCRIBE cannot be used because redis-cli will not accept any commands and can only quit the mode with Ctrl-C. However, if RESP3 is used (see HELLO), a client can issue any commands while in the subscribed state. The commands that are allowed in the context of a subscribed RESP2 client are: The replies to subscription and unsubscribing operations are sent in the form of messages so that the client can just read a coherent stream of messages where the first element indicates the type of message. Subscribers receive the messages in the order that the messages are published.Ī client subscribed to one or more channels shouldn't issue commands, although it can SUBSCRIBE and UNSUBSCRIBE to and from other channels. Messages sent by other clients to these channels will be pushed by Redis to all the subscribed clients.
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